Direct Isopropanol Fuel Cell

ABSTRACT

A direct isopropanol fuel cell adapted for use in ambient conditions and utilizing as fuel isopropanol and water preferably with isopropanol at relatively high concentrations representing 30% to 90% isopropanol.

SCOPE OF THE INVENTION

This invention relates to direct isopropanol fuel cells and, moreparticularly, an arrangement for a direct isopropanol fuel cell and amethod of operating the same.

BACKGROUND OF THE INVENTION

Direct alcohol fuel cells are known, and methanol is one of the mostcommon fuels for direct alcohol fuel cells.

The present applicant has appreciated that isopropanol is a fuel whichcan advantageously be used in direct alcohol fuel cells. Isopropanol hasadvantages that it is relatively inexpensive. Isopropanol has a lowrelative toxicity. Isopropanol is mixable with water. The presentapplicants have appreciated that direct isopropanol fuel cells are notcurrently available which serve many practical needs. For example, theapplicants have appreciated that direct isopropanol fuel cells are notknown which can operate under both ambient and sub-ambient temperatureconditions and/or over extended periods of time.

Fluid dispensers and notably dispensers of hand cleaning fluids areknown. The present applicants have appreciated that such dispenserssuffer the disadvantage that a practical electrical power generatingfuel cell is not currently available which can provide electrical powerto a dispenser over long periods of time at ambient temperatures.

SUMMARY OF THE INVENTION

To at least partially overcome some of these disadvantages, the presentinvention provides a direct isopropanol fuel cell utilizing as fuel amixture of isopropanol and water with isopropanol at relatively highconcentration and preferably adapted for use in ambient conditions.

To at least partially overcome some of these disadvantages, the presentinvention also provides a dispenser of hand cleaning fluid comprising amixture of isopropanol and water powered by a direct isopropanol fuelcell using as fuel the hand cleaning fluid.

In one preferred embodiment, the present invention provides a directisopropanol fuel cell comprising: a proton conducting or exchangemembrane with a cathode side and an anode side, a cathode having acathode catalyst on the cathode side of the membrane and an anodecatalyst on the anode side of the membrane such that the membrane isarranged between the cathode and the anode, a fuel supply unitconfigured to supply a liquid fuel to the anode, and an air supply unitconfigured to supply air to the cathode. The present invention alsoprovides a method of use of such a direct isopropanol fuel cell byoperating the direct fuel cell to generate electricity by supplying theanode with a liquid fuel and supplying the cathode with atmospheric aircontaining oxygen. The proton conducting or exchange membrane maycomprise different commercially available membranes and preferablycomprises a sulfonated poly(aryl ketone) membrane. The anode catalyst ispreferably selected from the group of a platinum and ruthenium catalyst,a platinum and nickel catalyst, a platinum and gold catalyst, andmixtures thereof. The cathode catalyst preferably comprises a platinumcatalyst, for example, platinum black. The liquid fuel preferablycomprises isopropanol and water in contact with the anode catalyst onthe anode side of the proton exchange membrane. The fuel cell mayprovide all electrical power to a fluid dispenser necessary to operatethe dispenser. Preferably, the dispenser is a dispenser whichautomatically dispenses fluid and requires electrical power forcontrolled dispensing of a fluid. Preferably, the dispenser is adispenser of a disinfecting and/or cleaning fluid, more preferably, adispenser of hand cleaning fluid on to a person's hands. Preferably, thehand cleaning fluid is a mixture of isopropanol and water. Preferably,the same fluid dispensed onto a person's hands as a cleaner is used asfuel for the fuel cell.

In one aspect the present invention provides a direct isopropanol fuelcell comprising:

a proton conducting or exchange membrane with a cathode side and ananode side,

a cathode having a cathode catalyst on the cathode side of the membraneand a anode catalyst on the anode side of the membrane such that themembrane is arranged between the cathode and the anode,

a fuel supply unit configured to supply a liquid fuel to the anode,

an air supply unit configured to supply air to the cathode,

the anode catalyst is selected from the group of a platinum andruthenium catalyst, a platinum and nickel catalyst, a platinum and goldcatalyst, and mixtures thereof,

the cathode catalyst comprises a platinum catalyst,

the liquid fuel consisting of 10% to 90% by volume isopropanol, 90% to10% by volume water and 0% to 30% by volume acetone in contact with theanode catalyst on the anode side of the membrane. Preferably, themembrane is a sulfonated poly(aryl ketone) membrane.

In another aspect the present invention provides a method of use of adirect isopropanol fuel cell, comprising:

providing a direct fuel cell comprising:

a proton conducting or exchange membrane with a cathode side and ananode side,

a cathode having a cathode catalyst on the cathode side of the membraneand a anode catalyst on the anode side of the membrane such that themembrane is arranged between the cathode and the anode,

operating the direct fuel cell to generate electricity by supplying theanode with a liquid fuel and supplying the cathode with atmospheric aircontaining oxygen;

the anode catalyst is selected from the group of a platinum andruthenium catalyst, a platinum and nickel catalyst, a platinum and goldcatalyst, and mixtures thereof,

the cathode catalyst comprises a platinum catalyst

the liquid fuel consisting of 10% to 90% by volume isopropanol, 90% to10% by volume water and 0% to 30% by volume acetone in contact with theanode catalyst on the anode side of the membrane. Preferably, the fuelcell is operated at ambient temperatures. Preferably, the protonexchange membrane is a sulfonated poly(aryl ketone) membrane.

Fuel

Preferably, the fuel consists of merely isopropanol and water preferablywithout any impurities, however, small amounts of impurities and othercompounds may be present provided the impurities and other compounds donot negatively affect the performance of the fuel cell. The fuelpreferably consists of isopropanol and water. The fuel preferablyconsists of a fuel selected from the group consisting of: 10% to 90% byvolume isopropanol and 90% to 10% by volume water; 40% to 90% by volumeisopropanol and 60% to 10% by volume water; 60 to 80% by volumeisopropanol and 40% to 20% by volume water; and 65% to 75% by volumeisopropanol and 35% to 25% by volume water. One preferred fuel is 70% byvolume isopropanol and 30% water by volume.

Preferably, the liquid fuel comprises 60 to 80% by volume isopropanoland 40% to 20% by volume water. Another preferred liquid fuel comprises65% to 75% by volume isopropanol and 35% to 25% by volume water.

The fuel may include acetone as in a range of 0% to 30% by volumeacetone. The acetone preferably does not exceed 30% by volume and, morepreferably, does not exceed 5% by volume. The fuel preferably aside fromacetone is free of any substantial impurities. The fuel may consist of afuel selected from the group consisting of: 10% to 90% by volumeisopropanol, 90% to 10% by volume water and 0 to 30% by volume acetone;40% to 90% by volume isopropanol, 60% to 10% by volume water and 0 to30% by volume acetone; 60% to 80% by volume isopropanol, 40% to 20% byvolume water and 0 to 20% by volume acetone; and 65% to 75% by volumeisopropanol, 35% to 25% by volume water, and 0 to 5% by volume acetone.

In accordance with some embodiments of the present invention, the fuelcell recycles the fuel from a fuel reservoir to an anode fuel chamber inwhich case the composition of the fuel may change with operation of thefuel cell and such recycling. The fuels referred to above are intendedto represent the virgin fuel supplied to the reservoir prior to anyrecycling and, as indicated above, preferably has the compositionsreferred to above and, more preferably, consist of isopropanol andwater.

In one embodiment of this invention, the fuel cell provides electricalpower to operate a dispenser of hand cleaning fluid and these samepreferred isopropanol and water mixtures are used both as the handcleaning fluid to be dispensed onto a person's hands and as the fuel forthe fuel cell.

In this application, all percentages of the components of the liquidfuel are percentages by volume considered at atmospheric pressure and atemperature of 20° C.

Isopropanol is appreciated by the applicant as being the smallestsecondary alcohol.

The preferred fuel of mixtures of isopropanol with water are liquids atambient temperatures and easy to store.

One advantageous use of isopropanol in relatively high concentrations ina water solution is that the solution is resistant to freezing undermost ambient temperatures to which the fuel cell may be exposedincluding temperature below freezing such as temperatures as low as −40degrees Celsius; −25 degrees Celsius; −20 degrees Celsius and −15degrees Celsius. Suitable selection of the fuel and the relativeproportions of isopropanol and water can assist in permitting use in lowtemperatures without freezing.

Proton Exchange Membrane

In a preferred fuel cell in accordance with the present invention, theproton conducting or exchange membrane (PEM) may comprise many differentknown membranes. The membrane preferably comprises sulfonated poly(arylketone) membrane, however, other commercially available membranes may beused. The sulfonated poly(aryl ketone) membrane comprises a sulfonatedpoly ether ketone membrane (SPEK); or a sulfonated poly ether etherketone membrane (SPEEK).

The sulfonated poly(aryl ketone membrane and particularly the SPEK isselected as it has been found to provide relatively low uptake of thefuel compared to perflorinated acid (PFA) type type PEM such as thatsold under the trade mark Nafion. The preferred sulfonated SPEK has arelatively small expansion when contacted with the fuel and preferablyexpands and contracts merely about 10%. This makes the sulfonated SPEKmembrane easier to handle since it does not swell as much as other knownPEM such as PFA type PEM. A saturated SPEK PEM has been found to have arelatively lower permeation rate than a saturated PFA type PEM.

A fuel cell assembly in accordance with the present invention needs tobe operated in a manner which prevents the PEM from drying out duringuse or storage and thus must be kept moistened with the liquid fuelduring use and storage.

Membrane Electrode Assembly

The fuel cell preferably incorporates a membrane electrode assembly(MEA) comprising a layered assembly of: (1) an anode gas diffusion layer(GDL), (2) an anode catalyst layer, (3) the proton conducting orexchange membrane, (4) a cathode catalyst layer, and (5) a cathode gasdiffusion layer (GDL), in that order.

The membrane electrode assembly is preferably disposed between a cathodecurrent collector on the cathode side of the membrane and an anodecurrent collector on the anode side of the membrane.

In the PEM fuel cell, the redox half reactions are kept separate at thecathode and anode respectively. The MEA includes the proton exchangemembrane that separates the two half reactions allowing protons to passthrough the proton exchange membrane to complete the overall reaction.An electron created on the anode side is forced to flow through anexternal circuit thereby creating current. The MEA consists of theproton exchange membrane, the two disbursed catalyst layers and the twogas diffusion layers (GDL). Each GDL allows direct and uniform access ofthe fuel and oxidant to the respective catalyst layer so as to permiteach respective half reaction. Thus, the anode GDL permits the fluid toaccess the catalyst layer between the anode GDL and the proton exchangemembrane. The anode GDL allows the isopropanol fuel to reach the anodecatalyst and thus for the reactive half reaction to occur. The cathodeGDL permits oxygen from the air to pass through the cathode GDL tosearch the cathode catalyst intermediate the cathode GDL and themembrane. The cathode GDL thus allows access of the O2 oxidant to thecathode catalyst layer to provide the oxidation half reaction.

In a single PEM cell which is the preferred form of the presentinvention, a cathode current collector is provided outwardly of the GDLwhich assists in the carrying current away from the cell and permits thepassage of the O2 oxidant from the air into the cell.

The cathode current collector is preferably in accordance with thepresent invention a conductive mesh or conductive wire screen withopenings there through which permit ready passage of oxygen from the airthrough to the cathode GDL. Similarly, the anode current collectorserves the function of carrying current away from the cell, permitsdistribution of the liquid fuel into the cell through the anode currentcollector to the anode GDL. The anode current collector preferably alsocomprises a conductive porous sheet or conductive wire mesh that permitsthe liquid fuel to pass through it to the anode GDL. Each of the anodeGDL and the cathode GDL preferably allow the direct and uniform accessof the liquid fuel and the O2 oxidant to their respective anode andcathode layers.

Target Reactions

The preferred fuel cell is preferably configured and operated such thatat the anode catalyst, isopropanol is principally reduced to acetoneplus two hydrogen ions in accordance with the following formula

[CH₃CHOHCH3]>[CH₃COCH₃+2H⁺+2e]

Thus, the fuel cell is preferably operated such that the principalreaction at the anode catalyst is to reduce a molecule of isopropanolinto a molecule of acetone releasing two electrons. The variouscomponents of the fuel cell, the fuel and the operating conditions andthe catalysts, notably the anode catalysts, are and have been preferablyselected to principally result in this preferred reaction. Variousoperational parameters may be monitored and operation may be selectedhaving regard to the monitored parameters to promote advantageousoperation and notably operation enhancing and optimizing the preferredreaction. Operational parameters which can be monitored and/orcontrolled include the electrical potentials between the anode and thecathode, the power density and the current density.

The applicants have appreciated that the operation of the fuel cell atspecific electrical potentials between the anode and the cathodeincreases the extent to which the isopropanol is principally reduced toacetone plus two hydrogen ions. In accordance with the presentinvention, the fuel cell is preferably operated at electrical potentialsbetween the anode and cathode such that the principal reaction at theanode catalyst is to reduce a molecule of isopropanol into a molecule ofacetone releasing two electrons. Preferably, the invention the fuel cellis preferably operated at electrical potentials between the anode andcathode above at least an electrical potential of 200 mV and, morepreferably, not below 300 my and, more preferably, in a range of betweenabout 400 mV and 500 mV.

Under some conditions of operation of a direct isopropanol fuel cellcarbon dioxide may be produced by reactions at the anode catalyst. Atthe same time, carbon monoxide is produced as an intermediary.Production of carbon monoxide is disadvantageous. The applicants haveappreciated that the operation of the fuel cell at lower electricalpotentials between the anode and the cathode increases the carbonmonoxide production. In accordance with the present invention, the fuelcell is preferably operated at electrical potentials between the anodeand cathode sufficiently high that reactions with the fuel at the anodecatalyst does not produce carbon dioxide. The fuel cell is preferablyoperated at electrical potentials between the anode and cathode notlower than 200 mV and, more preferably, not lower than 300 mV.

Various operational conditions in characteristics of the fuel cell inaccordance with the present invention can be determined by monitoringthe open circuit potential. The open circuit potential is defined as theelectrical potential between the anode and the cathode under no loadconditions. In accordance with the present invention sensors areprovided to monitor the open circuit potential.

After operating the fuel cell for a period of time, the open circuitpotential has been determined to reduce. It is believed that thereduction of the open circuit potential with time arises at least inpart due to dehydration of the PEM and/or poisoning of the anodecatalyst by carbon monoxide (CO) being produced on the catalyst andsitting on the catalyst. Control of the level of hydration of the PEM ispreferably achieved by monitoring the open circuit potential andsupplying fuel to the PEM. A preferred operation includes monitoring theopen cell potential between the anode and the cathode to determine whenthe open cell potential falls below a preselected rest threshold.Preferably, operating the pump when the open cell potential is below apreselected rest threshold. Thus, in accordance with the invention, itis assumed that the open cell potential is at least in partrepresentative of a low hydration level of the membrane, and the fuelcell is operated so as to maintain the hydration level of the membraneabove a minimum threshold level.

In operation with the preferred reaction acetone is created at the anodecatalyst by the oxidation of isopropanol. In accordance with the presentinvention, the fuel cell is configured and its various componentsselected to permit, and the fuel cell operates such that acetone createdat the anode catalyst passes through the membrane to the cathode side ofthe proton conducting or exchange membrane into communication with theatmosphere and the acetone evaporates into the atmosphere. This isadvantageous particularly in an arrangement in which fuel is recycled tothe anode catalyst as one vehicle in limiting the levels of acetone thatmay develop in the fuel. Nevertheless, surprisingly in experimentaltests, acetone levels in fuel have been found at levels as high as 30%by volume to cause no degradation of the performance of the fuel cell.At the anode catalyst, isopropanol is oxidized to acetone. In accordancewith the present invention, the operation of the fuel cell has not befound to degrade as the percent of acetone in the fuel cell may increaseTests have shown that when the fuel contains 5% to 30% of acetone,surprisingly, there is not a significant degradation in the performanceof the fuel cell. Acetone has a boiling point of approximately 6° C.whereas isopropanol has a boiling point of about 83° C. Selectiveevaporation of the acetone to the atmosphere from the cathode GDL asthrough an air chamber passively open to the atmosphere may be onemechanism which reduces the level of acetone in the fuel as may berecycled within a closed fuel system.

An advantage of the fuel cell in accordance with the present inventionis that the liquid fuel of isopropanol and the reaction product ofacetone do not significantly break down into carbon dioxide or othercomponents.

Ambient Operating Conditions

Preferably, the fuel cell is operated under ambient conditions, that is,under ambient conditions of temperature and pressure. Ambient pressureis typically atmospheric pressure. Ambient temperatures may, forexample, include relatively extreme temperature ranges as may beexperienced in various outdoor and indoor environments such as, forexample, without limitation temperatures in ranges of: from −40 degreesCelsius to +50 degrees Celsius, −25 degrees Celsius to −50 degreesCelsius, 0 degrees Celsius to +40 degrees Celsius and +5 degrees Celsiusto +40 degrees Celsius. Ambient temperatures may, for example, includecontrolled environment indoor temperature ranges as may be experiencedin various buildings and vehicles such as in ranges of: from +10 degreesCelsius to +30 degrees Celsius.

Operating the fuel cell under ambient conditions includes providingatmospheric air to the fuel cell at ambient temperature, and storing andsupplying the liquid fuel at ambient temperatures.

The configuration of the fuel cell, its components and the mixtures ofthe isopropanol and water fuel may be selected having regard to theambient conditions in which the fuel cell is to operate.

Catalyst Poisoning

During operation of the fuel cell the anode and/or the cathode which mayhave become poisoned by products of reactions at the respective anodeand cathode. Periodically, while the fuel cell is not subject to anelectrical load, a rejuvenation procedure may be performed. Monitoringthe open circuit potential can provide an indication that the anodecatalyst has been rejuvenated. The rejuvenation procedure may includepermitting the fuel cell to be inactive that is to have no load appliedto it. The rejuvenation procedure may include applying a reversedelectrical potential between the anode and the cathode to rejuvenate theanode and/or the cathode by the removal of poisoning products ofreactions at the respective anode and cathode.

For example, carbon monoxide may be created and become deposited on theanode catalyst. Such carbon monoxide can reduce the efficiency of theanode catalyst in promoting oxidation of the fuel this poisoning thecatalyst over time. The fuel cell is preferably operated so as tomaintain the level of carbon monoxide on the anode catalyst below aminimum threshold level. A low open cell potential is at least in partrepresentative of a high level of carbon monoxide on the anode catalyst.Preferably, the fuel cell is operated to monitor the open cell potentialbetween the anode and the cathode to determine when the carbon monoxideon the anode catalyst may exceed desired level as determined at least inpart by a determination that the open cell potential falls below apreselected rest threshold. In a rejuvenation procedure, a reversedelectrical potential may be applied between the anode and the cathodefor a period of time to oxidize any carbon monoxide deposited on theanode catalyst.

Air Breathing/Passive Fuel Cell

In accordance with the present invention, preferably, the cathode ispassively open to the atmosphere at least when the fuel cell is operatedto generate electrical power. With the cathode open the atmosphere, thefuel cell is an air breathing fuel cell. At least on the cathode airside the fuel cell may be considered a passive fuel cell since the fuelcell is preferably operated without any prime mover to move the air tothe fuel cell as is advantageous in reducing the energy consumptionrequired to operate a positive or forced air delivery system. While notpreferred, an active air supply system may be provided as to forceatmospheric air to flow past the cathode, however, such an active airsupply system is not preferred as it results in the consumption ofelectrical power to move the air.

Preferably, the fuel cell arrangement is provided with a mechanism toclose the passive communication of atmospheric air with the cathode sideof the MEA electrode. This can be advantageous as, for example, toreduce evaporation from the MEA as when the fuel cell is not in use togenerate electrical power or in other operational modes as, for example,during catalyst regeneration. The fuel cell has the air supply unitconfigured to supply air to the cathode. The air supply unit preferablyincludes an air chamber disposed adjacent to the cathode and having airopenings from the air chamber to the cathode with the air chamber opento the atmosphere air. The air supply unit may further include a closuremember movable between an open position permitting the atmospheric airand the cathode side of the proton electrode membrane to be passively incommunication and a closed position sealing the cathode side of the PEMfrom communication with the atmospheric air. The air supply unit mayinclude a mechanism to move the closure member between the open positionand the closed position. The fuel cell may be operated maintaining theclosure member in the open position during operation of the fuel cell togenerate electrical power, and maintaining the closure member in theclosed position while the fuel cell is not subject to an electricalload. For example, operation may include periodically maintaining theclosure member in the closed position while the fuel cell is not subjectto an electrical load to regenerate the cathode catalyst and/or anodecatalyst.

Fuel Supply Unit

The fuel cell includes a fuel supply unit configured to supply a liquidfuel to the anode. The fuel supply unit preferably includes an enclosedanode fuel chamber open to the anode on the anode side of the membrane.The anode fuel chamber may have an inlet preferably at an upper end andan outlet, preferably at a lower end. The fuel supply unit may includean enclosed fuel reservoir spaced from the anode fuel chamber with areturn passageway connecting the outlet of the fuel chamber with thefuel reservoir, and a delivery passageway connecting the inlet of theanode fuel chamber. Preferably, a fuel pump is provided to draw fuelfrom the reservoir and discharge the fuel into the anode fuel chambervia the inlet. Preferably, the fuel is recycled between the reservoirand the anode fuel chamber. The fuel reservoir may be located at aheight below the anode fuel chamber. The fuel may drain under gravityfrom the anode fuel chamber to the reservoir.

The fuel supply unit further includes a fuel supply container containingfuel separate from the reservoir for supply of fuel to the reservoir.The supply container is preferably located at a height above the fuelreservoir and includes a supply passageway to supply fuel from thesupply container to the fuel reservoir under gravity. A one way fuellevel maintaining valve may be disposed across the supply passageway topermit flow of fuel from the supply container to the fuel reservoirunder gravity only when a level of fluid in the fuel reservoir is belowa predetermined level.

The fuel pump is provided to provide the fuel to an anode fuel chamberin contact with the anode side of the membrane electrode assembly.However, towards conserving the energy required to operate the fuelcell, the fuel pump is preferably driven only intermittently havingregard to various factors including notably but without limitationdehydration of the membrane electrode assembly, and evaporative lossfrom the cathode air side of the membrane electrode assembly.

Various methods may be provided for operation of the fuel cell. Onepreferred method includes during operation of the fuel cell to generateelectrical power, operating the fuel cell in a cycle of operationincluding a first step of operating the fuel pump for a first period oftime to fill the fuel chamber with fuel, and a second step of notoperating the pump for a second period of time. In a fuel cell which hasthe closure member for controlling air communication the operation mayinclude, while maintaining the closure member in the closed positionwhile the fuel cell is not subject to an electrical load, operating thefuel cell in a cycle of operation including a first step of operatingthe fuel pump for a first period of time to fill the fuel chamber withfuel, and a second step of not operating the pump for a second period oftime, and wherein during the second step of not operating the pump,monitoring the open cell potential between the anode and the cathode andrecommencing the cycle with the first step of operating the pump whenthe open cell potential falls below a preselected rest thresholdrepresentative of a low hydration level of the membrane so as tomaintain the hydration level of the membrane above a minimum thresholdlevel.

As another method of operation, the anode fuel chamber is maintainedfilled with the liquid fuel or a vapor of the liquid fuel and reactantproducts of the reaction of the fuel at the anode so as to preventatmospheric air passing through the fuel chamber to the anode side ofthe proton electrode membrane.

End Plate Construction

A preferred fuel cell of this invention includes an anode end plate anda cathode end plate. The end plates may be constructed of anon-conductive material such as preferably a polymer. Each end plate maybe injection molded and/or machined from a unitary element to reduce thenumber of components.

The anode end plate has an inward anode face and an outward anode face.The cathode end plate has an inward cathode face and an outward cathodeface. The anode end plate and the cathode end plate are drawn togetherwith inward anode face in sealed engagement with the cathode end platesandwiching the membrane electrode assembly between the cathode currentcollector on the cathode side of the membrane electrode assembly and theanode current collector on the anode side of the membrane electrodeassembly. Preferably, the fuel supply unit includes an enclosed anodefuel chamber open to the anode on the anode side of the membraneelectrode assembly, and the fuel chamber is defined between the cathodeend plate and the anode end plate within an anode fuel cavity open tothe anode inward face towards the cathode end plate. Preferably, the airsupply unit includes an air chamber disposed adjacent to the cathode andhaving air openings from the air chamber to the cathode, the air chamberopen to the atmosphere air. Preferably, the air chamber is definedwithin the cathode end plate as an air cavity open outwardly to thecathode outer face and with the air openings extending inwardly from theair chamber to the cathode inward face, preferably with the air openingsbeing open through the cathode inward face to the cathode currentcollector of the cathode on the cathode side of the membrane.Preferably, the air supply unit further includes a closure membercoupled to the fuel cell for movement between an open positionpermitting the atmospheric air to be passively in communication with theair chamber and a closed position preventing the air chamber fromcommunication with the atmospheric air. A closure mechanism is mountedto the fuel cell to move the closure member between the open positionand the closed position. The closure member may comprise a platepivotably mounted the cathode plate for pivotal motion movement betweenthe open position in which the plate is spaced from the outer cathodeface and the closed position in which the plate is proximate the outercathode face. The closure mechanism may comprise an electric motor and alinkage mechanism wherein a relative rotational position of an outputshaft of the motor determines the relative location of the closuremember between the open and the closed position.

The present invention provides various concepts including:

As concept 1, a method of use of a direct isopropanol fuel cell,comprising:

providing a direct fuel cell comprising:

a proton conducting or exchange membrane with a cathode side and ananode side,

a cathode having a cathode catalyst on the cathode side of the membraneand a anode catalyst on the anode side of the membrane such that themembrane is arranged between the cathode and the anode,

operating the direct fuel cell to generate electricity by supplying theanode with a liquid fuel and supplying the cathode with atmospheric aircontaining oxygen;

wherein the membrane comprising a sulfonated poly(aryl ketone) membrane,

the anode catalyst is selected from the group of a platinum andruthenium catalyst, a platinum and nickel catalyst, a platinum and goldcatalyst, and mixtures thereof,

the cathode catalyst comprises a platinum catalyst,

the liquid fuel consisting of 10% to 90% by volume isopropanol, 90% to10% by volume water and 0% to 30% by volume acetone in contact with theanode catalyst on the anode side of the membrane.

As concept 2, a method as in concept 1 including operating the fuel cellat ambient temperatures.

As concept 3, a method as in concept 2 including providing atmosphericair at ambient temperature, and storing and supplying the liquid fuel atambient temperatures.

As concept 4, a method as in concepts 1 to 3 wherein the anode catalystconsists of the platinum and ruthenium catalyst.

As concept 5, a method as in concepts 1 to 4 wherein the membranecomprises a sulfonated poly(aryl ketone) membrane.

As concept 6, a method as in concepts 1 to 4 wherein the membranecomprises a sulfonated poly(aryl ketone) membrane selected from thegroup consisting of: (a) a sulfonated poly ether ketone membrane (SPEK);and (b) a sulfonated poly ether ether ketone membrane (SPEEK).

As concept 7, a method as in concepts 1 to 6 wherein the cathodecatalyst is a platinum black catalyst.

As concept 8, a method as in concepts 1 to 7 wherein during operation ofthe fuel cell to generate electrical power, the atmospheric air and thecathode side of the membrane are passively in communication.

As concept 9, a method as in concept 8 including:

providing a closure member movable between an open position permittingthe atmospheric air and the cathode side of the membrane to be passivelyin communication and a closed position sealing the cathode side of themembrane from communication with the atmospheric air, and

maintaining the closure member in the open position during operation ofthe fuel cell to generate electrical power, and maintaining the closuremember in the closed position while the fuel cell is not subject to anelectrical load.

As concept 10, a method as in concept 9 including periodicallymaintaining the closure member in the closed position while the fuelcell is not subject to an electrical load to regenerate the cathodecatalyst and/or the anode catalyst.

As concept 11, a method as in concepts 1 to 10 wherein the fuel cellcomprises a membrane electrode assembly,

the membrane electrode assembly comprising a layered assembly of ananode gas diffusion layer, an anode catalyst layer, the membrane, acathode catalyst layer, and a cathode gas diffusion layer in that order.

As concept 12, a method as in concept 11 wherein the membrane electrodeassembly is between a cathode current collector on the cathode side ofthe membrane and an anode current collector on the anode side of themembrane.

As concept 13, a method as in concepts 1 to 11 including operating thefuel cell such that the principal reaction at the anode catalyst is tooxidize a molecule of isopropanol into a molecule of acetone releasingtwo electrons.

As concept 14, a method as in concepts 1 to 12 including operating thefuel cell at electrical potentials between the anode and cathodesufficiently high that the principal reaction at the anode catalyst isto oxidize a molecule of isopropanol into a molecule of acetonereleasing two electrons.

As concept 15, a method as in concepts 1 to 13 wherein the fuel cell isoperated at electrical potentials between the anode and cathodesufficiently high that reactions with the fuel at the anode catalystdoes not produce carbon dioxide.

As concept 16, a method as in concepts 1 to 13 wherein the fuel cell isoperated at electrical potentials between the anode and cathode greaterthan 200 mV.

As concept 17, a method as in concepts 1 to 13 wherein the fuel cell isoperated at electrical potentials between the anode and cathode greaterthan 300 mV.

As concept 18, a method as in concepts 1 to 13 wherein the fuel cell isoperated at electrical potentials between the anode and cathode in therange of 300 mV to 400 mV.

As concept 19, a method as in concepts 1 to 18 including operating thefuel cell to create acetone at the anode catalyst by the oxidation ofisopropanol, providing for the acetone to pass through the membrane tocathode side of the membrane into communication with the atmospheric andevaporating the acetone into the atmosphere.

As concept 20, a method as in concepts 1 to 18 providing the fuel cellwith an enclosed anode fuel chamber open to the anode side of themembrane and having an inlet at an upper end and a drain outlet at alower end, an enclosed fuel reservoir located at a height below theanode fuel chamber, a drain passageway connecting the drain outlet ofthe fuel chamber with the fuel reservoir, and a fuel pump to draw fuelfrom the fuel reservoir and discharge the fuel into the anode fuelchamber via the inlet, operating the pump periodically to discharge thefuel into the anode fuel chamber.

As concept 21, a method as in concept 19 including permitting fuel inthe anode fuel chamber to flow from the anode fuel chamber to the fuelreservoir via the drain passageway.

As concept 22, a method as in concept 19 or 20 including monitoring theopen cell potential between the anode and the cathode to determine whenthe open cell potential falls below a preselected rest threshold.

As concept 23, a method as in concept 21 including operating of the pumpwhen the open cell potential is below a preselected rest threshold.

As concept 24, a method as in concepts 21 to 22 wherein the open cellpotential is at least in part representative of a low hydration level ofthe membrane, and operating the fuel cell so as to maintain thehydration level of the membrane above a minimum threshold level.

As concept 25, a method as in concepts 21 to 23 wherein during operationof the fuel cell to generate electrical power, carbon monoxide iscreated at the anode catalyst and becomes deposited on the anodecatalyst reducing the efficiency of the anode catalyst in promoting thereduction of the fuel,

the open cell potential is at least in part representative of a highlevel of carbon monoxide on the anode catalyst, and operating the fuelcell so as to maintain the level of carbon monoxide on the anodecatalyst below a minimum threshold level.

As concept 26, a method as in concepts 19 to 24 including duringoperation of the fuel cell to generate electrical power, operating thefuel cell in a cycle of operation including a first step of operatingthe pump for a first period of time to fill the anode fuel chamber withfuel and a second step of not operating the pump for a second period oftime.

As concept 27, a method as in concepts 19 to 25 wherein whilemaintaining the closure member in the closed position while the fuelcell is not subject to an electrical load including:

operating the fuel cell in a cycle of operation including a first stepof operating the pump for a first period of time to fill the anode fuelchamber with fuel, and a second step of not operating the pump for asecond period of time, and

wherein during the second step of not operating the pump monitoring theopen cell potential between the anode and the cathode and recommencingthe cycle with the first step of operating the pump when the open cellpotential falls below a preselected rest threshold representative of alow hydration level of the membrane so as to maintain the hydrationlevel of the membrane above a minimum threshold level.

As concept 28, a method as in concepts 19 to 26 including maintainingthe anode fuel chamber filled with the liquid fuel or a vapor of theliquid fuel and reactant products of the reaction of the fuel at theanode so as to prevent atmospheric air passing through the fuel chamberto the anode side of the membrane.

As concept 29, a method as in concept 26 wherein while maintaining theclosure member in the closed position while the fuel cell is not subjectto an electrical load including applying a revered electrical potentialbetween the anode and the cathode to rejuvenate the anode and/or thecathode which may have become poisoned by products of reactions at therespective anode and cathode.

As concept 30, a method as in concept 26 wherein while maintaining theclosure member in the closed position while the fuel cell is not subjectto an electrical load, applying a reversed electrical potential betweenthe anode and the cathode for a period of time to oxidize any carbonmonoxide deposited on the anode catalyst as a product of a reaction atthe anode catalyst.

As concept 31, a method as in any one of concepts 1 to 29 includingoperating the fuel cell at ambient temperatures in the range of minus 25degrees Celsius to plus 50 degrees Celsius.

As concept 32, a method as in any one of concepts 1 to 29 includingoperating the fuel cell at ambient temperatures in the range of 0degrees Celsius to plus 50 degrees Celsius.

As concept 33, a method as in any one of concepts 1 to 29 includingoperating the fuel cell at ambient temperatures in the range of minus 15degrees Celsius to plus 50 degrees Celsius.

As concept 34, a method as in any one of concepts 1 to 29 includingoperating the fuel cell at ambient temperatures in the range of plus 5degrees Celsius to plus 40 degrees Celsius.

As concept 35, a direct isopropanol fuel cell comprising:

a proton conducting or exchange membrane with a cathode side and ananode side,

a cathode having a cathode catalyst on the cathode side of the membraneand a anode catalyst on the anode side of the membrane such that themembrane is arranged between the cathode and the anode,

a fuel supply unit configured to supply a liquid fuel to the anode,

an air supply unit configured to supply air to the cathode,

the anode catalyst is selected from the group of a platinum andruthenium catalyst, a platinum and nickel catalyst, a platinum and goldcatalyst, and mixtures thereof,

the cathode catalyst comprises a platinum catalyst,

the liquid fuel consisting of 10% to 90% by volume isopropanol, 90% to10% by volume water and 0% to 30% by volume acetone in contact with theanode catalyst on the anode side of the membrane.

As concept 36, a fuel cell as in concept 34 wherein the anode catalystconsists of the platinum and ruthenium catalyst.

As concept 37, a fuel cell as in concepts 34 to 35 wherein the membranecomprises a sulfonated poly(aryl ketone) membrane.

As concept 38, a fuel cell as in concepts 34 to 36 wherein the membranecomprises a sulfonated poly(aryl ketone) membrane selected from thegroup consisting of: (a) a sulfonated poly ether ether ketone membrane(SPEEK); and (b) a sulfonated poly ether ketone membrane (SPEK).

As concept 39, a fuel cell as in concepts 34 to 37 wherein the cathodecatalyst is a platinum black catalyst.

As concept 40, a fuel cell as in concepts 34 to 37 wherein the fuelsupply unit includes an enclosed anode fuel chamber open to the anode onthe anode side of the membrane.

As concept 41, a fuel cell as in concept 39 wherein:

the anode fuel chamber having an inlet at an upper end and a drainoutlet at a lower end,

the fuel supply unit further includes an enclosed fuel reservoir spacedfrom the anode fuel chamber, a drain passageway connecting the drainoutlet of the fuel chamber with the fuel reservoir, and a fuel pump todraw fuel from the fuel reservoir and discharge the fuel into the anodefuel chamber via the inlet.

As concept 42, a fuel cell as in concept 40 wherein the fuel reservoiris located at a height below anode fuel chamber.

As concept 43, a fuel cell as in concept 40 wherein the fuel supply unitfurther including a fuel supply container containing fuel,

the supply container is located at a height above the fuel reservoir,

a supply passageway to supply fuel from the supply container to the fuelreservoir under gravity,

a one-way fuel level maintaining valve disposed across the supplypassageway to permit flow of fuel from the supply container to the fuelreservoir under gravity only when a level of fluid in the fuel reservoiris below a predetermined level.

As concept 44, a fuel cell as in concepts 34 to 42 wherein the airsupply unit includes an air chamber disposed adjacent to the cathode andhaving air openings from the air chamber to the cathode, the air chamberopen to the atmosphere air.

As concept 45, a fuel cell as in concept 43 wherein the air supply unitfurther includes a closure member movable between an open positionpermitting the atmospheric air and the cathode side of the membrane tobe passively in communication and a closed position sealing the cathodeside of the membrane from communication with the atmospheric air.

As concept 46, a fuel cell as in concept 44 wherein the air supply unitfurther comprising a mechanism to move the closure member between theopen position and the closed position, the fuel cell comprises amembrane electrode assembly.

As concept 47, a fuel cell as in concepts 34 to 45 wherein the membraneelectrode assembly comprises a layered assembly of an anode catalystlayer, an anode gas diffusion layer, the membrane, a cathode gasdiffusion layer and a cathode catalyst layer in that order.

As concept 48, a fuel cell as in concept 46 wherein the membraneelectrode assembly is between a cathode current collector of the cathodeon the cathode side of the membrane and an anode current collector ofthe anode on the anode side of the membrane.

As concept 49, a fuel cell as in concept 47 including an anode end plateand a cathode end plate,

the anode end plate having an inward anode face and an outward anodeface, the cathode end plate having an inward cathode face and an outwardcathode face,

the anode end plate and the cathode end plate are drawn together withinward anode face in sealed engagement with the cathode end platesandwiching the anode and the cathode therebetween with the membraneelectrode assembly between the cathode current collector of the cathodeon the cathode side of the membrane and the anode current collector ofthe anode on the anode side of the membrane.

As concept 50, a fuel cell as in concept 48 wherein:

the fuel supply unit includes an enclosed anode fuel chamber open to theanode on the anode side of the membrane,

the fuel chamber defined between the cathode end plate and the anode endplate within an anode fuel cavity open to the anode inward face towardsthe cathode end plate.

As concept 51, a fuel cell as in concept 49 wherein the air supply unitincludes an air chamber disposed adjacent to the cathode and having airopenings from the air chamber to the cathode, the air chamber open tothe atmosphere air,

the air chamber defined within the cathode end plate as an air cavityopen outwardly to the cathode outer face and with the air openingsextending inwardly from the air chamber to the cathode inner face,

the air openings open through the cathode inner face to the cathodecurrent collector of the cathode on the cathode side of the membrane.

As concept 52, a fuel cell as in concept 43 wherein the air supply unitfurther includes a closure member coupled to the fuel cell for movementbetween an open position permitting the atmospheric air to be passivelyin communication with the air chamber and a closed position preventingthe air chamber from communication with the atmospheric air.

As concept 53, a fuel cell as in concept 51 wherein the air supply unitfurther comprising a closure mechanism mounted to the fuel cell to movethe closure member between the open position and the closed position.

As concept 54, a fuel cell as in concept 51 wherein the closure membercomprises a plate is pivotably mounted the cathode plate for pivotalmotion movement between the open position in which the plate is spacedfrom the outer anode face and the closed position in which the plate isproximate the outer anode face,

the closure mechanism comprising an electric motor and a linkagemechanism wherein a relative rotational position of an output shaft ofthe motor determines the relative location of the closure member betweenthe open and the closed position.

As concept 55, a fuel cell as in concept 49 wherein the anode fuelchamber having an inlet at an upper end and a drain outlet at a lowerend,

the fuel supply unit further includes an enclosed fuel reservoir spacedfrom the anode fuel chamber, a drain passageway connecting the drainoutlet of the fuel chamber with the feel reservoir, and a fuel pump todraw fuel from the reservoir and discharge the fuel into the anode fuelchamber via the inlet.

As concept 56, a fuel cell as in concept 54 wherein the fuel reservoiris located at a height below anode fuel chamber.

As concept 57, the method of concepts 1 to 34 wherein the fuel consistof a fuel selected from the group consisting of:

40% to 90% by volume isopropanol and 60% to 10% by volume water;

60% to 80% by volume isopropanol and 40% to 20% by volume water; and

65% to 75% by volume isopropanol and 35% to 25% by volume water.

As concept 58, the method of concepts 1 to 34 wherein the fuel consistof a fuel selected from the group consisting of:

40% to 90% by volume isopropanol, 60% to 10% by volume water and 0 to30% by volume acetone;

60% to 80% by volume isopropanol, 40% to 20% by volume water and 0 to20% by volume acetone; and

65% to 75% by volume isopropanol, 35% to 25% by volume water, and 0 to5% by volume acetone.

As concept 59, the method of concepts 1 to 34 including:

providing the fuel cell with an anode fuel chamber open to the anodeside of the membrane and a fuel reservoir,

transferring the fuel from the reservoir to the anode fuel chamber andreturning the fuel from the anode fuel chamber to the reservoir,

including supplying the fuel to the reservoir,

wherein the fuel supplied to the reservoir consisting of a fuel selectedfrom the group consisting of:

40% to 90% by volume isopropanol and 60% to 10% by volume water;

60% to 80% by volume isopropanol and 40% to 20% by volume water; and

65% to 75% by volume isopropanol and 35% to 25% by volume water.

As concept 60, a fuel cell as in any one of concepts 35 to 59 incombination with a dispenser of hand cleaning fluid which requireselectrical power to dispense a cleaning fluid onto a hand of a personusing the dispenser, and wherein the fuel cell supplies all electricalpower required for operation of the dispenser.

As concept 61, a fuel cell as in concept 60 wherein the dispenserdispensing as a hand cleaner the same fluid used as the fuel for thefuel cell.

As concept 62, a fuel cell as in concept 60 or 61 wherein the dispenserdispenses fluid with an electrically powered dispensing pump when anelectrically powered sensing system senses the presence of a user'shand.

BRIEF DESCRIPTION OF THE DRAWINGS

Further aspects and advantages of the present invention will appear fromthe following description taken together with the accompanying drawingsin which:

FIG. 1 is a schematic view of a fuel cell arrangement in accordance witha first embodiment of the present invention;

FIG. 2 is a schematic view of a fuel cell arrangement in accordance witha second embodiment of the present invention;

FIG. 3 is a pictorial front and top view of a fuel cell assembly inaccordance with the second embodiment with an air closure cover in aclosed position;

FIG. 4 is a pictorial view of the fuel cell assembly of FIG. 3 with theair closure cover in an open position;

FIG. 5 is a pictorial view of the fuel cell apparatus of FIG. 3 with theair closure cover, the cover movement mechanism and a motor for a fluidpump removed so as to show an assembled plate assembly;

FIG. 6 is an exploded pictorial front view of the plate assembly of FIG.5 with a fluid pump removed;

FIG. 7 is an exploded pictorial rear view of the cathode end plate andthe anode end plate of FIG. 6;

FIG. 8 is a pictorial front view of the anode end plate of FIG. 7,however, drawn as though the material forming the anode end plate istransparent;

FIG. 9 is a partially cross-sectioned pictorial front side view of thetransparent anode end plate of FIG. 8 along section line A-A′ in FIG. 8;

FIG. 10 is a partially cross-sectioned pictorial front bottom view ofthe transparent anode end plate of FIG. 8 along cross-section line B-B′in FIG. 8;

FIG. 11 is a schematic pictorial view of the layered assembly shown inFIG. 6;

FIG. 12 is a partial cross-sectional side view of the assembled plateassembly along section line C-C′ in FIG. 5;

FIG. 13 is a partial cross-section side view of the anode end plate ofFIG. 8 along the cross-section line A-A′ but also showing a fuel pumpassembly coupled to the anode plate;

FIG. 14 is a schematic pictorial view of a pump casing, two pump gearsand an O-ring of the fuel pump assembly of FIG. 13;

FIG. 15 is a cross-sectional view along section D-D′ FIG. 13;

FIG. 16 is a pictorial view of a liquid feeder of the fuel cell of FIG.6;

FIG. 17 is a partial cross-sectional view through the feeder of FIG. 16when s coupled to the anode end plate as in FIG. 6;

FIG. 18 is a graph showing during operation of a first configuration ofa fuel cell in accordance with the present invention for a period oftime shortly after start-up of the fuel cell, the fuel cell voltage, thefuel cell current and the voltage of the buffer battery as measured atdifferent points in time;

FIG. 19 is a graph showing, for the same fuel cell as in FIG. 18, duringoperation for a period of time after operation of the fuel cell ofalmost six months following the start-up of the fuel cell, the fuel cellvoltage, the fuel cell current and the voltage of the buffer battery asmeasured at different points in time;

FIG. 20 is a graph showing during operation of a second configuration ofa fuel cell in accordance with the present invention for a period oftime shortly after start-up of the fuel cell, the fuel cell voltage, thefuel cell current and the voltage of the buffer battery as measured atdifferent points in time;

FIG. 21 is a graph showing, for the same fuel cell as in FIG. 20, duringoperation for a period of time after operation of the fuel cell ofalmost six weeks following the start-up of the fuel cell, the fuel cellvoltage, the fuel cell current and the voltage of the buffer battery asmeasured at different points in time;

FIG. 22 is a schematic view of a fuel cell arrangement in combination ofa fluid dispenser in accordance with a third embodiment of the presentinvention; and

FIG. 23 is a schematic view of a fuel cell arrangement in combinationwith a fluid dispensing arrangement in accordance with a fourthembodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

Reference is made to FIG. 1 which is a schematic view of a fuel cellarrangement 10 in accordance with a first embodiment of the presentinvention. The fuel cell arrangement 10 notably includes a powergenerator 12 which provides a number of elements sandwiched togetherbetween on the right hand side, an anode end plate 14, and on the lefthand side, a cathode end plate 15. A membrane electrode assembly (MEA)16 is provided in the center with an anode current collector 26 betweenthe MEA 16 and the anode end plate 14 and a cathode current collector 27between the cathode end plate 15 and the MEA 16.

The MEA 16 comprises five layers of which the center layer is a protonexchange membrane 20. On the right side of the proton conducting orexchange membrane 20 an anode catalyst 22 is provided. To the right ofthe anode catalyst 22, an anode gas diffusion layer (GDL) 24 is providedbeside the anode current collector 26. On the left hand side of theproton electrode membrane 20, a cathode catalyst 23 is provided. To theleft of the cathode catalyst 23 a cathode gas diffusion layer (GDL) 25is provided beside the cathode current collector 27.

To the left laterally outwardly of the cathode current collector 27, anair chamber 29 is defined within the cathode end plate 15. The airchamber 29 is open outwardly to the atmosphere via air openings 31through the cathode end plate 15. On the right hand side the anode endplate 14 defines therein an anode fuel chamber 28 opening inwardlythrough the anode current collector 26 to the anode GDL 24. The anodefuel chamber 28 closed otherwise other than at a fuel chamber inlet 30at an upper end of the anode fuel chamber 28 and a fuel chamber outlet32 at a lower end of the anode fuel chamber 28.

A fuel reservoir 34 is provided at a height below the anode fuel chamber28. The fuel reservoir 34 is shown as an enclosed vessel with anenclosing wall 35. An air vent tube 289 provides an air vent passageway36 through the wall 35 to the atmosphere so as to provide forequalization of the pressure inside the fuel reservoir 34 with theatmospheric air as, for example, to relieve any vacuum which may bedeveloped within the fuel reservoir 34 as fuel is consumed by the fuelcell. A fuel chamber drain tube 290 provides a drain passageway 37 fromfuel chamber outlet 32 to a drain tube outlet 291 in the fuel reservoir34 to permit fluid within the anode fuel chamber 28 to flow, as undergravity, from the anode fuel chamber 28 into the fuel reservoir 34. Areservoir outlet 38 is provided connected via a fuel pump feed tube 293providing a feed passageway 39 to a fuel pump 40. The fuel pump 40 isconnected via a fuel pump discharge tube 294 providing a dischargepassageway 41 to the fuel chamber inlet 30. The fuel pump 40 whenoperating draws fluid from the reservoir 34 via the feed passageway 39and discharges it via the discharge passageway 44 into the anode fuelchamber 28.

The anode current collector 26 comprises a conductive wire mesh orscreen. An anode lead wire 42 is electrically connected to the anodecollector 26 and extends upwardly therefrom. The cathode currentcollector 27 comprises a conductive wire mesh or screen. A cathode leadwire 43 is electronically connected to the cathode current collector 27.

The anode lead wire 42 and the cathode lead wire 43 are schematicallyillustrated as connected so as to have an electronic load L therebetweenas with electrons moving in the wires 42 and 43 in a direction indicatedby the arrows 45 when the fuel cell arrangement is operational to createelectrical energy. The load L is schematically illustrated as beingelectrically interconnected via a controller 47 to an electrical powerstorage device 46. The controller 47 is also electrically interconnectedwith an electric motor 48 to drive the fuel pump 40. In operation of thefuel cell arrangement 10 electrical power is generated by the cell 12 asschematically illustrated by the load L which power is under the controlof the controller 47 directed as to be stored in electrical powerstorage device 46 and/or the delivered to the pump motor 48 to drive thefuel pump 40. The controller 47 preferably includes various sensingdevices and capability to sense various aspects the operation of thefuel cell arrangement 10 the load L and the open circuit potentialpreferably over time. The electrical power storage device 46 maycomprise rechargeable batteries, capacitors and the like.

Reference is made to FIG. 2 which shows a fuel cell arrangement 10 inaccordance with a second embodiment of the present invention. The fuelcell arrangement 10 of FIG. 2 is identical to the fuel cell arrangementof FIG. 1, however, with the following additions.

As a first addition, an air closure cover 50 is provided mounted forpivoting about a pivot axis 51 from an open position as shown in FIG. 2which permits a free flow of atmospheric air through the air openings 31into the air chamber 29 and a closed position, not shown in FIG. 2, inwhich the air closure cover 50 pivots about the pivot axis 51 counterclockwise to engage the cathode end plate 15 and close the air openings31 preventing communication between the atmospheric air and the airchamber 29. A cover movement mechanism is provided to move the airclosure cover 50 between the open position and closed position includinga cover motor 52 coupled to the controller 47, and a linkage assembly 53connected between the cover motor 52 and the air closure cover 50 tomove the air closure cover 50 between the open and closed positions ascontrolled by the controller 47 selectively operating the motor 52.

As a second addition, a fuel supply container 54 is provided which may,for example, comprise a bottle. The container 54 has a container outlet55. The container 54 supplies the liquid fuel to the fuel reservoir 34to maintain the fuel reservoir 34 substantially full of fuel. In FIG. 2,the fuel supply container 54 is disposed at height above the fuelreservoir 34 and a gravity feed arrangement provides for the liquid fuelto flow under gravity from the fuel supply container 54 to the fuelreservoir 34. In this regard, a supply tube 295 provides a supplypassageway 56 that connects the container outlet 55 to a fuel levelcontrolling inlet valve 57 that opens into the fuel reservoir 34. Thefuel level controlling inlet valve 57 permits the liquid fuel to flowfrom the fuel supply container 54 into the fuel reservoir 34 only whenthe level of the fuel within the reservoir 34 is below a certain level.The fuel level controlling inlet valve 57 may preferably is of a simpleconstruction with a minimum of moving parts such as a preferred chickenfeeder type valve arrangement.

In FIG. 2, the air vent tube 289 is shown as preferably extendingupwardly to provide the upper end of the air vent passageway 36 at aheight above the height of the fuel within the fuel supply container 54.In a situation that the fuel level controlling inlet valve 57 maymalfunction, providing the upper end of the air vent passageway 36 abovethe fuel supply container 54 will prevent fuel from flowing undergravity out the upper end of the air vent passageway 36.

Reference is made to FIGS. 3 to 17 which illustrate a preferredconfiguration of selected elements of the fuel cell arrangement 10 shownschematically in FIG. 2.

In FIG. 3, the air closure cover 50 is pivotally mounted to the cathodeend plate 15 for pivoting about the pivot axis 51 disposed vertically inFIG. 3. The air closure cover 50 is movable between a closed position asshown in FIG. 3 and an open position as seen in FIG. 4. The cover motor52 is shown as being mounted to the anode end plate 14. The linkageassembly 53 includes a pivot arm 60 which is rotated by the cover motor52 about a horizontal axis 61 between a closed position shown in FIG. 3and an open position shown in FIG. 4. A link arm 62 is pivotallyconnected at one end to the air closure cover 50 radially spaced fromthe axis 51 and at the other end to a distal end of the pivot arm 61such that the relative rotational position of the pivot arm 61 about theaxis 61 will determine the extent to which the air closure cover 50 willbe located between the fully closed and the fully opened position.

The air closure cover 50 has a face plate 63 which in the closedposition is disposed to closely overly and engage an outer face 64 ofthe cathode end plate 15 to prevent air communication between theatmosphere and the air chamber 29.

Reference is made to FIG. 5 which illustrates a pictorial view of thefuel cell arrangement of FIG. 3 but with the air closure cover 50, thecover motor 52, the linkage assembly 53 and the pump motor 48 removedfor ease of illustration. FIG. 5 shows what is referred to as anassembled plate assembly 66. The components of the plate assembly 66which are visible in FIG. 5 are notably the anode end plate 14 and thecathode end plate 15. The anode lead wire 42 and the cathode lead wire43 are shown extending upwardly from between the anode end plate 14 andthe cathode end plate 15. The anode end plate 14 and the cathode endplate 15 are fixedly secured together as by various fasteners whichextend through complementary openings provided through the cathode endplate 14 and the anode end plate 14 from an outer face 64 of the cathodeend plate 15 to an outer face 65 of the anode end plate 14. In FIG. 7,one threaded bolt 301 and one complementary nut 302 are shown inexploded view as arranged for coupling through aligned openings 303 and304 through the plates 14 and 15.

Reference is made to FIG. 6 which shows an exploded front view of theplate assembly 66 shown in FIG. 5. FIG. 6 shows a layered assembly 112that is received between the cathode end plate 15 and the anode endplate 14. Referring to FIG. 11, the assembly 112 is schematically shown.The MEA 16 is shown as a relatively thin rectangular sheet. On oppositesides of the MEA 16 are the anode current collector 26 and the cathodecurrent collector 27, each of which in the form of a rectangular sheetof similar size to the MEA 16. Each of the anode current collector 26and the cathode current collector 27 are preferably a conductive mesh orscreening, preferably of stainless steel and which provides bothmechanical support and an electrode to which the respective anode leadwire 42 with the cathode lead wire 43 may be mechanically andelectrically secured. Each of the anode current collector 26 and thecathode current collector 27 suitably permit air and fuel and othermaterials to pass there through as between the air chamber 29 and theMEA 16 on the anode side 72 of the MEA 16 and as between the anode fuelchamber 28 and the MEA 16 on the cathode side 73 of the MEA 16.

Outwardly of the anode current collector 26 and the cathode currentcollector 27 are provided an anode seal 68 and a cathode seal 69,respectively. Each of the seals 68 and 69 is also shown as a rectangularsheet, however, of a size both in width and height larger than therectangular sheets forming the MEA 16, the anode current collector 26and the cathode current collector 27. On each of the seals 68 and 69,there is a border portion 70 between their circumferential edges and adashed line. The border portion 70 of the anode seal 68 is adapted toengage and seal to the border portion 70 the cathode seal 69 forming animpermeable seal circumferentially thereabout. A central portion 71 ofeach of the seals 68 and 69 inside the border portion 70 is provided soas to suitably permit air and fuel and other materials to pass therethrough as between the air chamber 29 and the MEA 16 on the anode side72 of the MEA 16 and as between the anode fuel chamber 28 and the MEA 16on the cathode side 73 of the MEA 16. The joined border portions 70 ofthe seals 68 and 69 are sized to be complementary to the circumferentialextent of a cell cavity 175 in the inner face 75 of the cathode endplate 15 shown on FIG. 7. As best seen in FIG. 12, the joined borderportions 70 of the seals 68 and 69 are clamped in the cavity 175 betweenthe cathode end plate 14 and the anode end plate 15 with the centralportion 71 of the seal 68 open in to a fuel cavity 76 and the anode fuelchamber 28 in the anode end plate 14 and the central portion 71 of theseal 69 open to the atmosphere air via air openings 31 and the airchamber 29 in the cathode end plate 15. The border 70 of the seals 68and 69 sealably engages about the fuel cavity 76 preventingcommunication between the anode fuel chamber 28 and the air chamber 29other than through the central portions 71 of the seals 68 and 69 andthereby through various layers of the layered assembly 112 including theMEA 16.

Referring to FIGS. 6 and 7, the anode end plate 14 has an inner face 74disposed substantially in a flat plane and the cathode end plate 15 hasan inner face 75 also disposed in a substantially flat plane other thanover the cavity 175 and where two channels 142 and 143 are provided toaccommodate the lead wires 42 and 43. The inner face 74 of the cathodeend plate 14 is adapted to be maintained in engagement with the innerface 75 of the cathode end plate 15 in assembly of the plate assembly 66with the layered assembly 112 therebetween.

Referring to FIG. 6, the anode end plate 14 has three cavities definedtherein, namely, a fuel cavity 76, a reservoir cavity 77 and a pumpcavity 78.

Proximate the upper end of the anode end plate 14, the fuel cavity 76 isprovided. The fuel cavity 76 has a rectangular configuration having arectangular outer wall 201, a top wall 202 a bottom wall 203, a rightside wall 204 and left side wall 205. The fuel cavity 76 defines anenclosed cavity open at an opening 200 through the inner face 74 of theanode end plate 14 as seen in FIG. 6.

The anode end plate 14 carries the reservoir cavity 77 below the fuelcavity 76. The reservoir cavity 77 has an outer wall 206 and a top wall207, bottom wall 208, left side wall 209 and a right side wall includingportions 210, 211 and 212 of which portion 211 is horizontal as shown.The reservoir cavity 77 opens outwardly as an opening 214 through theinner face 74 of the anode end plate 14. A sealing bead 215 is providedin the inner face 74 of the anode end plate extending circumferentiallyabout the opening 214 of the reservoir cavity 77. The sealing bead 215assists in engagement with the inner face 75 of the cathode end plate 15when the cathode end plate 15 and the anode end plate 14 are drawntogether so as to provide a fluid impermeable seal therebetween. Withthe anode end plate 14 and the cathode end plate 15 secured together,the opening 214 of the reservoir cavity 77 is enclosed by the inner face75 of the cathode end plate 15 is forming the reservoir 34 cavitytherebetween.

As can be seen in FIG. 8, a pump cavity 78 is also formed in the anodeend plate 14. The pump cavity 78 has an outer wall 216 and an ovalperipheral side wall 217 with a pump opening 218 through the inner face74 the anode end plate 14. The structure of the pump cavity 78 isdescribed later in greater detail with reference to FIGS. 13 to 15.

As can be seen from FIGS. 6 and 7, the outer face 64 of the cathode endplate 15 had a pair of air chambers 29 defined therein separated by ahorizontally extending support flange 220. Each air chamber 29 has anoutwardly facing inner wall 221 ordered by respective top, bottom, leftside and right side walls 222, 223, 224 and 225, respectively. Aplurality of air openings 31 are provided from the inner wall 21 throughthe cathode end plate 15 to the inner face 75. As can best be seen in acomparison of the front view of FIG. 6 and the rear view of FIG. 7, eachof these air openings 31 is located in registry with the fuel cavity 76.When the layered assembly 112 is engaged within the fuel cavity 76, theair openings 31 provide communication from the air chamber 29 to thecentral portions 71 of the cathode seal 69.

Reference is made to FIGS. 8 to 10 which illustrate the anode end plate14 as advantageously formed from a single unitary member of preferablyof plastic or other non-electrically conducting material and from whichselected portions of the material are removed to provide desiredstructures such as the cavities and passageways. In FIGS. 8 to 10 forease of illustration, the anode end plate 14 is schematically shown asthough the anode end plate 14 is formed from a transparent material.

In a top wall 80 of the anode end plate 14 the upper ends of fourvertically extending bores are shown.

A vertical pump bore 240 extends from the top wall 80 through pumpcavity 78 to the horizontal portion 210 of the side wall of thereservoir cavity 77. The vertical pump bore 240 opens at the top wall 80as a pump bore upper opening 241. A horizontal pump bore 242 is cut fromthe fuel cavity 76 right side 204 horizontally to the vertical pump bore240. A separate element, a pump bore plug 243, is engaged within theupper end of the vertical pump bore 240 after the vertical pump bore 240is formed to sealably close the vertical pump bore 240 against fluidflow. The vertical pump bore 240 above the pump cavity 78 and thehorizontal pump bore 242 form the discharge passageway 41. The verticalpump bore 240 below the pump cavity 78 forms the feed passageway 39.When the fuel pump 40 is received within the pump cavity 78, operationof the fuel pump 40 draws fluid from the reservoir cavity 77 anddischarges fuel into the fuel cavity 76 by flow through the verticalpump bore 240 and the horizontal pump bore 242. FIG. 10 illustrates across-sectional view centered on the vertical pump bore 240 and bestshowing the passageways 39 and 41 and the pump bore plug 243. The pumpbore 240 is disposed laterally to the right side of the fuel cavity 76and does not interfere with the fuel cavity 76.

A vertical drain bore 246 extends vertically downwardly from the topwall 80 through the top wall 207 into the reservoir cavity 77. Thevertical drain bore 246 opens at an upper opening 248 in the top wall 80of the anode end plate 14. A separate element, a drain bore plug 249, isreceived and closes the opening 248 to fluid flow after the verticaldrain bore 246 is formed to sealably close the vertical drain bore 246against fluid flow. A horizontal drain bore 247 extends from the leftside wall 205 of the fuel cavity 76 horizontally into the vertical drainbore 246. The vertical drain bore 246 and the horizontal drain bore 247define the drain passageway 37 for communication between the fuel cavity76 and the reservoir cavity 77. The drain bore 244 is disposed laterallyto the left side of the fuel cavity 76 and does not interfere with thefuel cavity 76.

A vent bore 244 extends vertically downwardly from the top wall 80through the top wall 207 into the reservoir cavity 77 providing the airvent passageway 36 therein. The vent bore 244 opens through the top wall207 of the reservoir cavity 77 as an opening 245. The vent bore 244 isdisposed laterally to the left side of the fuel cavity 76 and does notinterfere with the fuel cavity 76.

A supply bore 252 extends vertically downwardly from the top wall 80through the top wall 207 into the reservoir cavity 77 providing thesupply passageway 56 therein. The supply bore 252 is disposed laterallyto the left side of the fuel cavity 76 and does not interfere with thefuel cavity 76. The supply bore 252 opens through the top wall 207 ofthe reservoir cavity 77 as an opening 254. The top wall 207 of thereservoir cavity 77 has about the opening 247 four short blind bores255. A separate element, a sump box member 250 is shown by itself inFIG. 16 and coupled to the anode end plate 14 in FIGS. 6 and 17. Thesump box member 250 carries four upwardly extending securing pegs 257adapted to be frictionally received within the blind bores 248 to securethe sump box member 250 to the anode end plate 14. The sump box member250 is a rectangular box closed on its bottom and four sides but openupwardly at its top. On one side an opening 259 is provided through aside wall 258. As can be seen in FIG. 17 in an assembled condition,another separate element, a dip tube 260 is secured in the supply bore256 and extends downwardly to a lower end 261 of the dip tube 260. Thesump box member 250 forms an enclosed feed chamber 262 about the diptube 254 sealably engaged with the top wall 207 at its upper end andopen into the reservoir merely via the opening 259. The lowermostportion of the opening 259 is at a vertical height H above the lower end261 of the dip tube 260. On the basis that gas or vapour is providedwithin the fuel reservoir 34, fluid flow from the supply container 54will only occur when a hydraulic pressure due to the height of fluid inthe supply container 54 is adequate to displace fluid within the feedchamber 262 upwardly to the height of the opening 259. The sump boxmember 250, the dip tube 260 and the anode end plate 14 thus cooperateto form a liquid feeder, as in the manner of a known chicken feeder, andthe fuel level controlling inlet valve 57 of FIG. 2.

The particular nature of the fuel level controlling inlet valve 57 isnot limited and various other valve arrangements may be provided forcontrolling the supply of fuel from the fuel supply container 54 to thefuel reservoir 34 under gravity. It is considered preferred to providefor the fuel supply container 54 so as to provide a larger supply offuel than the capacity of fuel reservoir 34 to increase the energy andduration that the fuel cell may operate. A separate fuel supplycontainer 54 is not necessary and is for example not provided in theembodiment of FIG. 1. The particular nature of fuel reservoir 34 may beadjusted to its size and location and manner in which it may beincorporated into or external of the plates 14 and 15 of fuel cellarrangement 10 as in FIG. 1.

Providing for flow of fuel from the fuel supply container 54 into thefuel reservoir 34 by gravity as controlled by the fuel level controllinginlet valve 57 shown as a mechanical valve is preferred so as to notrequire any expenditure of the energy generated by the fuel cell as todeliver fuel from the fuel supply container 54 to the fuel reservoir 34.Alternately, with the fuel supply container 54 above the fuel reservoir34, an electrical solenoid valve may form the fuel level controllinginlet valve 35 as controlled by the controller and with a fuel levelsensor provided within the fuel reservoir 34 to determine when fuel fromthe fuel supply container 54 may be permitted to flow under gravity tothe fuel reservoir 34, as another alternative, a supply pump may beprovided to pump fuel from the fuel supply container 54 into the fuelreservoir 34 as controlled by the controller with a fuel level sensorwithin the fuel reservoir 34.

In an assembled fuel cell, as seen in FIG. 12 in cross-section, theanode fuel chamber 28 is defined inside the fuel cavity 76 outwardly ofthe layered assembly 112 effectively defining a vertically extendingfluid flow field of constant cross-section within the anode fuel chamber28 via which fuel may flow from the fuel chamber inlet 30 to the fuelchamber outlet 32. The outer wall 201 of the fuel cavity 76 is shown asdisposed in a flat vertical plane. As an alternative, the outer wall 201may be provided with a raised boss in a serpentine shape having aninwardly directed inner surface disposed in a flat plane and sidesurfaces such that a serpentine shaped flow channel is provided betweenthe side surfaces leading from the fuel chamber inlet 30 to the fuelcamber outlet 32.

Reference is made to FIGS. 13 to 15 which illustrate a preferred pumparrangement for the fuel pump 40 and its pump motor 48 in accordancewith the present invention. The pump arrangement has a configurationsimilar in many respects to that illustrated in U.S. Pat. No. 5,836,482to Ophardt et al., issued Nov. 17, 1998, the disclosure of which isincorporated herein by reference. The fuel pump 40 is a gear type rotarypump with two inter-machine gear-like impellers, namely, a driverimpeller 146 and a driven impeller 148, received in a cavity within apump casing 152. The casing 152 is adopted to be slidably inserted in asealed manner within the pump cavity 78 and has a complimentary shapeand side. The impellers 146 and 148 are identical with each adapted tobe rotated about its respective axis 162 and 163. Each impeller has agear portion 158 disposed coaxially about the axis with radially andaxially extending teeth 160. Each impeller has an axial member 164 whichextends axially from the gear portion 158 and serves to assist injournaling its impeller in the cavity 150. As seen in FIG. 14, thecavity 150 is formed so as to journal the impellers 146 and 148 forrotation with the axis of the impellers parallel, with the impellersdisposed beside each other and with the teeth of one impellerintermeshing with the teeth of the other impeller in a nip 166 betweenthe impellers. The cavity 150 carries two outwardly extending blindbores 165 sized to receive and journal axle members 164 of the impellersto journal the impellers. The cavity 150 has a circumferential side walldefined by part-cylindrical forming surface 170 disposed at a constantradius from the axis 162 of the driver impeller 146 and part-cylindricalforming surface 172 disposed at a constant radius from the axis 163 ofthe driven impeller 148. An inlet port 174 opens through the casing 152into the cavity 150 on the lower side of the cavity 150 below the nip166. Fluid in the fluid reservoir 34 is in communication with the cavity150 via the feed passageway 39. An outlet port 176 opens through thecasing 152 into the cavity in an upper side of the casing 150 above thenip 166. The driver impeller 146 has an axle extension rod 180 whichextends coaxially therefrom outwardly. The inner wall 216 of the motorcavity 78 has a horizontally inwardly extending projection 177complimentary in shape to the cavity 50. A bore extends horizontallythrough the projection 177 through which the extension rod 180 extendoutwardly. The bore includes an enlarged radius portion adapted toreceive a sealing washer 178 to sealably engage the extension rod 180.

The pump motor 48 is fixedly secured to the outer face 65 of the anodeend plate 14 and carries an axle 198 with a coupling 100 which extendsinto engagement with the extension rod 180 rotate the extension rod onrotation of the motor 48.

When the motor 180 rotates the driver impeller 146 clockwise in adirection of the arrow 188 shown in FIG. 15, the driver impeller 146engages the driven impeller 148 to rotate the driven impeller clockwisein a direction of the arrow 190. Fluid 18 in the cavity 150 approximatethe inlet port 174 is located in the space between adjacent teeth 160 ofeither of the impellers. On rotation of the teeth of the impellers awayfrom the inlet port 174, the fluid between the adjacent teeth becomesimpounded in spaces between the adjacent teeth 160 and the fluid soimpounded is moved with rotation of each impeller circumferentially fromnear the inlet port 74 upwardly to the outlet port 176. The intermeshingof the teeth 160 of the two gear-like portions in the nip 166 betweenthe impellers substantially displaces fluid from the spaces between theteeth in the nip 166 so as to in effect to prevent fluid from passingbetween the gear-like portions in the nip.

The particular nature of the pump motor showing is but one form of apump which can be conveniently adapted. Rather than coupling the motorto the driven impeller via shaft that extends through the anode endplate 14 and requires a seal, a magnetic coupling may be provided.Various other motors and various other fluid pump arrangements can beprovided without departing from the scope of the invention.

In accordance with a preferred operation of the fuel cell 10 of thefirst and second embodiments the present invention, the liquid fuel isrecirculated by the fuel pump 40 through the anode fuel chamber 28 andback to the fuel reservoir 34. This effectively is a closed circuit butfor any additional fuel which may be supplied from the fuel supplycontainer 54 in the second embodiment to maintain the fuel reservoir 34substantially filled with fluid. In the second embodiment, the fuelwhich may be received from the fuel supply container 54 will replacefuel which may be consumed in or evaporate from the fuel cell.

Experimental Results

A fuel cell as shown in FIGS. 3 to 17 was operated under varyingconfigurations and conditions.

In a first preferred configuration:

(a) The active surface area of the air and the fuel compartment were 50cm² each.

(b) The volume of the anode fuel chamber 28 was approximately 2 cm³.

(c) The volume of the fuel reservoir 34 was approximately 2 cm³. Thefuel was supplied from the fuel reservoir (approximately 2 cm³) and thespent fuel was discarded.

(d) The pumping capacity of the fuel pump was approximately 1000 ml perminute. Pumping was controlled by a timer, and approximately 5 cm³ werepumped every twenty minutes.

(e) The fuel cell was operated at ambient room temperatures of about 20degrees Celsius.

(f) The liquid fuel consisting of 70% by volume isopropanol and 30% byvolume water was used the following operational.

(g) The fuel cell was operated to produce electricity provided the opencircuit potential was above approximately 380 mV.

(h) The fuel cell was operated in intervals with load on for 60 secondsand load off for 60 seconds.

(i) In a second series of experiments, the intervals were modified asfollows: load on for 30 seconds and load off for 60 seconds.

(j) The fuel cell was connected to a dc/dc converter in order torecharge a buffer battery (consisting of four NiMH cells).

(k) The fuel cell was operated so as to maintain a stable batteryvoltage of approximately 5V.

(l) This fuel cell was operated in excess of five months.

(m) FIG. 18 shows the fuel cell voltage (Ecell [V]), the fuel cellcurrent (Icell [A]) and the voltage of the buffer battery (Ebat [V])during a charging period of Time in seconds shortly after fuel cellstart-up.

(n) FIG. 19 shows the same fuel cell after a period of operation ofalmost six months showing the fuel cell voltage (Ecell [V]), the fuelcell current (Icell [A]) and the voltage of the buffer battery (Ebat[V]) during a period of Time in seconds.

In a second preferred configuration:

(a) The active surface area of the air and the fuel compartment were 50cm³.

(b) The volume of the anode fuel chamber 28 was approximately 2 cm³.

(c) The liquid fuel consisting of 70% by volume isopropanol and 30% byvolume water was used the following operational.

(d) The fuel was supplied from a reservoir 34 with approximately 300 cm³volume and the spent fuel was recycled to this reservoir.

(e) A feeder 57 was used to refill the reservoir 34 automatically from afuel tank 54 with a volume of 300 cm³.

(f) The pumping capacity of the fuel pump was approximately 1000 ml perminute. Pumping was controlled by a timer, and approximately 5 cm³ werepumped every ten minutes.

(g) The fuel cell was operated at ambient room temperatures of about 20degrees Celsius.

(h) The fuel cell was operated to produce electricity provided thepotential under load was above approximately 380 mV.

(i) The fuel cell was operated in intervals with load on for 30 secondsand load off for 30 seconds.

(j) The fuel cell was connected to a dc/dc converter in order torecharge a buffer battery (consisting of four NiMH cells).

(k) The fuel cell was operated so as to maintain a stable batteryvoltage of approximately 5V.

(l) This fuel cell was operated in excess of six weeks.

(m) FIG. 20 shows the fuel cell voltage (E cell [V]), the fuel cellcurrent (I cell [A]) and the voltage of the buffer battery (E bat [V])during a charging period shortly after fuel cell start-up during aperiod of Time in seconds.

(n) FIG. 21 shows the same fuel cell after a period of operation ofalmost six weeks swing the fuel cell voltage (E cell [V]), the fuel cellcurrent (I cell [A]) and the voltage of the buffer battery (E bat [V])during a charging period shortly after fuel cell start-up during aperiod of Time in seconds.

Reference is made to FIG. 22 which illustrates as a third embodiment ofthe present invention a hand cleaning fluid dispenser 300 incorporatinga fuel cell arrangement. FIG. 23 illustrates a vertical cross-sectionalview through the fluid dispenser 300. The fluid dispenser 300 has aconfiguration substantially identical to that taught by above-noted U.S.Pat. No. 5,836,482, however, with a notable exception that a fuel cellarrangement is incorporated into the dispenser. The fuel cellarrangement 10 as shown in side view of FIG. 22 is the same as the fuelcell arrangement of FIGS. 3 to 17.

The dispenser 300 includes a fluid container 54 and, in this regard, thefuel cell arrangement 10 in FIG. 22 has a configuration identical tothat illustrated in the second embodiment of FIG. 2 with a supply tube295 serving to deliver liquid fuel from a container outlet 55 to thefuel reservoir 34 as by the feed tube 295 providing communication to afeed inlet port 253 on the anode end plate 14. Throughout all thedrawings, similar reference numerals are used to refer to similarelements.

The dispenser 300 includes a housing 310 adapted to be mountedvertically as to a wall. The housing 310 includes a front plate 390 anda rear plate 391 secured together. The front plate 390 and includes amotor casing 392 which carries internally a dispensing motor 382. Themotor casing 392 carries a forwardly open socket 308. The dispenser 300has a replaceable unit 312 which comprises both the supply container 54and a pump 320. The replaceable unit 312 is adapted to be removablycoupled to the housing 310 by forward and rearward movement with thecontainer 54 removably supported on a support shelf 332 of the frontplate and the dispensing pump 320 removably engaged within the socket308. A feed tube 340 connects the dispensing outlet 338 of the supplycontainer 54 with the pump 320. A one-way inlet valve 336 permits flowfrom the container 54 to the pump 320. When the replaceable unit 312 iscoupled to the housing 310, the pump 320 is operatively connected to theelectrical motor 382 such that operation of the dispensing motor 382drives the dispensing pump 320 to dispense liquid as from an outlet 344onto a person's hand disposed underneath the outlet 344 but not shown.Below the motor casing 392, the front plate 390 carries a sensingmechanism 336 to sense the presence of a user's hand underneath theoutlet 344 and to thereby as suitably controlled by the controller 47 todispense the cleaning fluid from the container 54 onto a person's hand.

Between the front plate 390 and the rear plate 391, a cavity 393 isschematically shown which extends downwardly past the lower end of thefront plate 390 where the cavity 393 opens forwardly. A protective rigidwire screen 394 extends between the rear plate 391 and the front plate390 below the front plate 390 in front of the cavity 393 to permit airflow into and out of the cavity 393. Within the cavity 393 below thefront plate 390, the fuel cell arrangement 10 is provided with the anodeend plate 14 fixedly secured to the rear plate 291 and carrying thecathode end plate 15 forwardly thereof. The cavity 393 is sized so as toaccommodate all of the components of the fuel cell arrangement 10providing sufficient room for the components such as those indicated inFIGS. 3 to 17 as the air closure cover 50, the cover motor 52, thelinkage assembly 53 and the pump motor 48, however, not shown on FIG.22. The wire screen 394 provides for free flow of atmospheric air intoand out of the cavity 393. The controller 47 and the electrical powerstorage device 46 are schematically illustrated within the cavity 393 aselectrically connected to various elements including electricalconnection to the anode and cathode of the fuel cell and the pump motorof the fuel cell as well as any other sensors that may be provided inconjunction with the fuel cell. The controller 47 is also connected tothe dispensing motor 382 and the sensing mechanism 336 to controloperation of the fluid dispenser 300. It is to be appreciated that manyother electrical components may be incorporated into the fluid dispenser300 electrically connected to and controlled by the controller 47including, for example, communication arrangements as, for example, forone or two-way communication as, for example, via a WiFi network withdevices remote from the dispenser 300.

The fuel cell arrangement 10 generates electrical power which is storedin the electrical power storage device 46 and is hence used by thecontroller 47 to operate the dispenser 300 as by sensing the presence ofa user's hand with the sensing mechanism 336 and, when a user's hand issensed, to operate the motor 382 to dispense a predetermined dose offluid. When fluid within the supply container 54 is exhausted, thereplaceable unit 312 may be removed and replaced by another unit. Insuch replacement, a quick connect and disconnect arrangement may beprovided between the supply tube 295 and the container outlet 55.

In FIG. 22, the fluid within the container 54 is dispensed directly ontoa person's hand to serve as a hand cleaning fluid and, as well, isdelivered directly to the fuel cell as a fuel for the fuel cell.Preferred fuels are isopropanol and water mixtures, preferablyconsisting merely of isopropanol and water without other components orany impurities which would impede the operation of the fuel cell or bedetrimental to contact with a person's hand. Preferred mixtures consistof 10% to 90% isopropanol and 90% to 10% water, more preferably 40% to90% isopropanol and 60% to 10% water. The other ranges of isopropanoland water fuels discussed with reference to the earlier embodiments areuseful in the embodiment of FIG. 22, however, with a preferred liquidcomprising 65% to 75% isopropanol and 35% to 25% water.

Reference is made to FIG. 23 which illustrates a fourth embodiment inaccordance with the present invention in which a hand cleaning fluiddispenser incorporates a fuel cell arrangement 10. The embodiment ofFIG. 23 is identical to the embodiment of FIG. 22 but for the exceptionthat the fuel supply container 54 is provided as a separate containerfrom a container 316 of fluid to be dispensed by the fluid dispenser 300onto a person's hand, and a discharge pump 400 is provided communicatingby a discharge passageway 401 with the fluid reservoir 34 for thedischarge of fuel from the fluid reservoir 35 via a passageway 402 intothe dispensing container 316. In the arrangement of FIG. 23, the supplycontainer 54 is filled with the isopropanol and water fuel and thecontainer 316 may be filled with the same or a different liquid orfluid.

In the embodiments of FIGS. 22 and 23, the supply container 54 may be arigid container open to the atmosphere or may comprise a collapsiblecontainer, for example, having the fuel within a sealed flexible plasticbag. Similarly, the dispensing fluid container 316 in FIG. 23 maycomprise a rigid container with some form of vacuum relief within thecontainer or a collapsible container.

The particular nature of the dispenser into which a fuel cellarrangement 10 in accordance with the present invention may beincorporated is not limited. Such fluid dispensers may serve manypurposes. In the context of the dispenser being a dispenser of cleaningfluids, it is particularly advantageous if the fuel may serve a dualpurpose of acting, on one hand, as a cleaning liquid for use in cleaningand, on the other hand, for use as a fuel in the fuel cell, however,this is not necessary.

In accordance with the embodiments of the dispensers illustrated in FIG.18, the liquid fuel which is provided to the fuel cell is recycledwithin the fuel cell and is not used as a cleaning fluid.

In accordance with the embodiment of the dispenser illustrated in FIG.23, the liquid fuel which is provided to the fuel cell is not onlyrecycled within the fuel cell but is also delivered to the dispensingcontainer 316 to be dispensed with the fluid in the dispensing container316 onto the person's hand and thus also used as the cleaning fluid.

The dispenser of FIG. 23 could similarly be configured to be similar tothe embodiment of FIG. 18 by eliminating the discharge pump 400, thedischarge passageway 401 and the passageway 402 in FIG. 23, such thatthe liquid fuel which is provided to the fuel cell is recycled withinthe fuel cell and is not used as a cleaning fluid. Conversely, thedispenser of FIG. 22 could be configured by providing a discharge pump400, a discharge passageway 401 and a passageway 402 as in FIG. 19, suchthat the liquid fuel which is provided to the fuel cell is recycled notonly within the fuel cell but also back to the supply container 54. Theembodiment of FIG. 22 could also be modified to eliminate the fuelreservoir 34 and merely use the supply container 54 to supply fuel tothe anode fuel chamber 28 with or without recycling.

In accordance with the present invention, fuel within the fuel cell maybe discharged from the outlet 344 of the dispenser 300 with the variousmechanisms being provided for transferring of the fuel within the fuelcell back to the supply container 54, the dispensing container 316 orotherwise to the dispenser 16 for discharge out the discharge outlet 344or the dispenser 16. FIG. 23 shows an arrangement with two fluidcontainers, namely, the dispensing fluid container 316 and the supplycontainer 54. An optional second dispensing pump 410 shown in dashedlines could be provided to deliver the fluid from the supply container54 via tubes 411 and 412 also shown in dashed lines to the dispensingoutlet 344. This second pump 410 could be controlled to dispense fluidto the dispensing outlet 344 simultaneously with the dispensing of thefluid from the dispensing fluid container 316, preferably with mixingprior to discharge, or separately. As one example, the fluid in thedispensing fluid container 316 might comprise components incompatiblewith use in the fuel cell such as alcohols other than isopropanol and/ormoisturizers and fragrances which would poison the catalysts. The fluidin the supply container 54 could provide a high concentration ofisopropanol in water and, on mixture with the fluid in the dispensingfluid container 316, a resultant dispensed fluid may have advantageouslyreduced concentrations of isopropanol. As another example, the fluid inthe dispensing fluid container 316 might comprise substantially waterwith or without components incompatible with use in the fuel cell. Thefluid in the supply container 54 could provide a high concentration ofisopropanol in water, and, on mixture with the fluid in the dispensingfluid container 316, a resultant dispensed fluid may have advantageouslyselected proportions of isopropanol and water, with the dispenser havinga capability to vary the proportions by varying the relative amounts ofeach fluid dispensed simultaneously.

In accordance with the present invention, with a fuel comprising amixture of isopropanol and water, a reaction product of acetone will,with operation of fuel cells, come to be present with the isopropanoland water within the anode fuel chamber 28 and the fuel reservoir 34.The presence of acetone in relatively minor concentrations, for example,less than 30% by volume and, more preferably, less than 5% by volume,does not have a negative effect on a person's skin and thus can betolerated in many applications where the dispensing fluid is to be usedto clean a person's hand. Of course, when the liquid fuel is deliveredfrom the fuel cell arrangement 10 into the dispensing fluid container316, the acetone will be diluted with the fluid within the dispensingcontainer 316. As well, the presence of acetone as, for example, up to30% by volume is not detrimental for many other cleaning uses or otherpurposes.

While the invention has been described with reference to preferredembodiments, many modifications and variations will now occur to personsskilled in the art. For a definition of the invention, reference is madeto the following claims.

We claim:
 1. A method of use of a direct isopropanol fuel cell,comprising: providing a direct fuel cell comprising: a proton conductingor exchange membrane with a cathode side and an anode side, a cathodehaving a cathode catalyst on the cathode side of the membrane and aanode catalyst on the anode side of the membrane such that the membraneis arranged between the cathode and the anode, operating the direct fuelcell to generate electricity by supplying the anode with a liquid fueland supplying the cathode with atmospheric air containing oxygen;wherein the membrane comprising a sulfonated poly(aryl ketone) membrane,the anode catalyst is selected from the group of a platinum andruthenium catalyst, a platinum and nickel catalyst, a platinum and goldcatalyst, and mixtures thereof, the cathode catalyst comprises aplatinum catalyst, the liquid fuel consisting of 10% to 90% by volumeisopropanol, 90% to 10% by volume water and 0% to 30% by volume acetonein contact with the anode catalyst on the anode side of the membrane. 2.A method as claimed in claim 1 including operating the fuel cell atambient temperatures, and providing atmospheric air at ambienttemperature, and storing and supplying the liquid fuel at ambienttemperatures.
 3. A method as claimed in claim 2 wherein during operationof the fuel cell to generate electrical power, the atmospheric air andthe cathode side of the membrane are passively in communication.
 4. Amethod as claimed in claim 3 including operating the fuel cell such thatthe principal reaction at the anode catalyst is to oxidize a molecule ofisopropanol into a molecule of acetone releasing two electrons.
 5. Amethod as claimed in claim 4 including operating the fuel cell atelectrical potentials between the anode and cathode sufficiently highthat the principal reaction at the anode catalyst is to oxidize amolecule of isopropanol into a molecule of acetone releasing twoelectrons.
 6. A method as claimed in claim 4 including operating thefuel cell to create acetone at the anode catalyst by the oxidation ofisopropanol, providing for the acetone to pass through the membrane tocathode side of the membrane into communication with the atmospheric andevaporating the acetone into the atmosphere.
 7. A method as claimed inclaim 4 including: providing a closure member movable between an openposition permitting the atmospheric air and the cathode side of themembrane to be passively in communication and a closed position sealingthe cathode side of the membrane from communication with the atmosphericair, and maintaining the closure member in the open position duringoperation of the fuel cell to generate electrical power, and maintainingthe closure member in the closed position while the fuel cell is notsubject to an electrical load.
 8. A method as claimed in claim 7including periodically maintaining the closure member in the closedposition while the fuel cell is not subject to an electrical load toregenerate the cathode catalyst and/or the anode catalyst.
 9. A methodas claimed in claim 8 providing the fuel cell with an enclosed anodefuel chamber open to the anode side of the membrane and having an inletat an upper end and a drain outlet at a lower end, an enclosed fuelreservoir located at a height below the anode fuel chamber, a drainpassageway connecting the drain outlet of the anode fuel chamber withthe fuel reservoir, and a fuel pump to draw fuel from the fuel reservoirand discharge the fuel into the anode fuel chamber via the inlet,operating the pump periodically to discharge the fuel into the anodefuel chamber, and permitting fuel in the anode fuel chamber to flow fromthe anode fuel chamber to the fuel reservoir via the drain passageway.10. A method as claimed in claim 9 including during operation of thefuel cell to generate electrical power, operating the fuel cell in acycle of operation including a first step of operating the pump for afirst period of time to fill the anode fuel chamber with fuel and asecond step of not operating the pump for a second period of time.
 11. Amethod as claimed in claim 10 wherein while maintaining the closuremember in the closed position while the fuel cell is not subject to anelectrical load including: operating the fuel cell in a cycle ofoperation including a first step of operating the pump for a firstperiod of time to fill the anode fuel chamber with fuel, and a secondstep of not operating the pump for a second period of time, and whereinduring the second step of not operating the pump monitoring the opencell potential between the anode and the cathode and recommencing thecycle with the first step of operating the pump when the open cellpotential falls below a preselected rest threshold representative of alow hydration level of the membrane so as to maintain the hydrationlevel of the membrane above a minimum threshold level.
 12. A method asclaimed in claim 11 wherein while maintaining the closure member in theclosed position while the fuel cell is not subject to an electrical loadincluding applying a revered electrical potential between the anode andthe cathode to rejuvenate the anode and/or the cathode which may havebecome poisoned by products of reactions at the respective anode andcathode.
 13. A method as claimed in claim 4 wherein the fuel cellcomprises a membrane electrode assembly, the membrane electrode assemblycomprising a layered assembly of an anode gas diffusion layer, an anodecatalyst layer, the membrane, a cathode catalyst layer, and a cathodegas diffusion layer in that order.
 14. A method as claimed in claim 13wherein the membrane electrode assembly is between a cathode currentcollector on the cathode side of the membrane and an anode currentcollector on the anode side of the membrane.
 15. A method as claimed inclaim 2 wherein the anode catalyst consists of the platinum andruthenium catalyst, and the cathode catalyst is a platinum blackcatalyst.
 16. A method as claimed in claim 15 wherein the membranecomprises a sulfonated poly(aryl ketone) membrane.
 17. A method asclaimed in claim 12 including monitoring the open cell potential betweenthe anode and the cathode to determine when the open cell potentialfalls below a preselected rest threshold, and operating of the pump whenthe open cell potential is below a preselected rest threshold.
 18. Amethod as claimed in claim 16 wherein the fuel cell is operated atelectrical potentials between the anode and cathode greater than 200 mV.19. A method as claimed in claim 18 including operating the fuel cell atambient temperatures in the range of plus 5 degrees Celsius to plus 40degrees Celsius.
 20. A method as claimed in claim 16 wherein the opencell potential is at least in part representative of a low hydrationlevel of the membrane, and operating the fuel cell so as to maintain thehydration level of the membrane above a minimum threshold level.